204 BULLETIN OP THE UNIVERSITY OF WISCONSIN. 



Cilia of a single row of cells or double at the base. 

 Capsule immersed or emergent. 



Teeth papillose, not vermicular striate . . 0. affine, 168. 



Teeth vermicular striate, not papillose 0. fastigiatum, $14. 



Capsule exserted. 



Teeth not papillose 0. Blyttii, 209. 



Teeth minutely papillose . . . .0. praemorsum, 226. 



c. Capsule ribbed only near the mouth. 



Teeth erect when dry. 



Papillae of leaves simple, minute .... 0. rupestre, 167. 

 Papillae of leaves bifurcate, salient ... 0. Killiasii, 225. 

 Teeth reflexed when dry. 



Upper part of leaf bistratose, teeth transversely lin- 



eolate . 0. Bolanderi, 167. 



Upper part of leaf unistratose, teeth very papillose. 

 Teeth when dry reflexed and applied to capsule 0. elegans, 224. 



Teeth when dry touching capsule only with tip 0. speciosum, 1 169. 



Three little known and unimportant species from Greenland (Mac. Cat. 

 88): OO. Breutelii Hpe., Barthii Sendtn., and Groenlandicum Bergg., 

 belonging to the division with superficial stomata are not included in the 

 key. According to Venturi in Husn. Muse. Gall. 175, the first two are 

 only forms of O. Blyttii. 



II. Stomata immersed. 

 i. Peristome simple, capsule costate. 



Leaves obtuse, capsule immersed or emergent 0. Jamesianum, 177. 



leaves acute or acuminate. 



Capsule long exserted, teeth erect when dry . 0. anomalnm, 164. 



Capsule half-emergent, teeth spreading when dry 0. cupulatum, 165. 

 [O. Hallii may be sought here.] 



2. Peristome double. 



a. Capsule smooth when dry. 



Cilia wider than teeth 0. exiguum, 174. 



Cilia narrow. 



Capsule gradually narrowed to seta .... 0. pallens, 175. 



Capsule abruptly contracted to seta . . 0. pusillum Mitt. 8 173. 



i See Appendix, no. 223. 

 8 O. psilocarpum James. 



